1. Field of the Invention
The present invention relates to a processing apparatus in which plasma is used and, more particularly, it relates to an apparatus for carrying out the etching or film-forming process in the course of manufacturing semiconductor devices, for example.
2. Description of the Related Art
Those processing apparatuses such as plasma etching and CVD ones wherein a plasma atmosphere is created in a vacuum processing chamber to plasma-process substrates housed therein to be processed are conventionally used in the course of manufacturing semiconductors. The apparatuses of this kind are intended to use the plasma of reactive gas generated by plasma generator means and to apply the etching or film-forming process to semiconductor wafers in the vacuum processing chamber.
As semiconductor devices are made finer, it is required that the semiconductor wafers can be more finely processed by the plasma process. In order to achieve this, the reactive gas must be made a plasma at a higher efficiency while keeping the degree of vacuum in the vacuum processing chamber higher.
As the degree of vacuum in the processing chamber is made higher and higher, the probability that gas particles collide with electrons is further reduced. When the degree of vacuum in the processing chamber is made high, therefore, it becomes difficult that the reactive gas is efficiently made plasma by the processing apparatus of the planar plasma type or by the RIE apparatus commonly-used. This makes it impossible for these conventional apparatuses to apply a fully fine process to the semiconductor wafers.
In order to solve this problem, a processing apparatus in which the magnetron plasma or ECR system is used has been proposed. The magnetron plasma system includes a means for generating a magnetic field parallel to the semiconductor wafers, and it is intended to create magnetron discharge by the magnetic field thus generated and by an electric field perpendicular to the magnetic field. On the other hand, the ECR system is intended to diffuse plasma flow along the diffusion field created by the magnetic field.
In the case of the magnetron plasma system, however, the reactive gas can be made plasma under some degree of vacuum but it is difficult to efficiently make it plasma under a higher degree of vacuum. In the case of the ECR system, the apparatus must be made larger in size, thereby making its cost higher.